Diamond shape guide

Round Brilliant Diamond Guide

Maximum brilliance. Timeless appeal.

What makes a good round brilliant diamond?

Because round brilliants are engineered around light return, cut quality deserves heavy weighting. GIA grades overall cut for standard D-to-Z round brilliant diamonds.

Proportions and face-up size

A round outline does not have a length-to-width decision in the same way fancy shapes do. Instead, pay attention to face-up diameter for the carat weight and whether excess depth is hiding weight.

Carat is weight; for rounds the shopping metric is face-up diameter in millimeters. A deep Excellent-cut stone can still look small next to a well-spread peer at the same carat—compare diameter first, then cut grade and video.

Color and clarity

Rounds often hide inclusions relatively well because of their busy brilliant facet pattern, but inclusion type and position still matter. Dark crystals under the table or reflective needles that flash in daylight deserve a closer look even inside VS grades.

On rounds, color differences between neighboring grades are often subtle once mounted—compare D–F versus G–H in your metal rather than paying for a letter you cannot see. Fluorescence is common; mild blue usually is not a problem unless the stone looks oily in daylight video.

What to inspect in 360° video

• Even brightness and a lively contrast pattern as the stone rotates—not long dark patches.
• Cut-related leakage: a dull “watery” look despite strong paper grades.
• Central or dark inclusions that remain obvious when you zoom out to normal scale.
• Paint/dig or other finish issues the listing photos may crop away.
• Whether the face-up diameter matches your size goal for the carat.

Best buying strategy

1. Filter for GIA (or equivalent) Excellent / Ideal cut, then Excellent polish and symmetry.
2. Set a diameter range in mm that matches the look you want, not only a carat number.
3. Choose the lowest color and clarity that still look right to you in video and metal context.
4. Reject lifeless stones even if the cut grade is top-tier on paper.
5. Compare at least three rounds with similar diameter and grades side-by-side.

Educational reference: GIA diamond-quality and shape guidance. Fancy-shape appearance varies materially from stone to stone, so ratios and measurements are screening tools rather than guarantees.